Process of making carbon articles.



ARTHUR a. HIN'CKLEY, or NIAGARA FALLS, Il'EW YORK, Assrmoe TO NATIONAL CARBON COMPANY, or CLEVELAND, onro, A CORPORATION or NEW JERSEY.

PROCESS OF MAKING CARBON ARTICLES.

No Drawing.

To all whom it may concern Be it known that I, ARTHUR T. II'IINOKLEY, a citizen of the United States, and a resident of Niagara Falls, in the county of Niagara, in the State of New York, have invented new and useful Improvements in the Process of Making Carbon Articles, of which the following is a clear and exact description.

My invention relates to the method of making carbonaceous articles such as furnace electrodes, brushes, contact blocks and other similar articles.

One object of the invention is to increase the apparent density of the carbon articles.

Another object is to permit the useof a greater percent. of binder without rendering the mix too plastic.

Another object is to prevent the swelling of the binder in a carbon article While it is being baked.

Another object is to shorten the temperature range through which the .binder is plastic in the process of-baking or in other words to shorten the time required for coking the binder.

Another object is to cause the gases escaping from the articles to deposit more of their carbon than is usual. V

Other objects will appear in the appended description.

Carbon articles are usually made by molding, tamping and forcing them into the desired form from a material or mixture consisting of an agglomeration of coke or other carbonaceous material and pitch. The mixture from which the articles are made is prepared by agglomerating coke, coal or other carbonaceous material with pitch, both being preferably in a powdered condition, in a vessel which is heated sufiiciently to melt the latter. If the mixture is to be forced through a die, care must be taken not to use more than a certain amount of pitch. If

more than the limiting amount is used the articles, especially the larger sizes, will not be rigid enough to retain their shape perfectly. If a large circular electrode is forced, forinstance, from a binder that contains too much pitch, it will not retain its circular shape, but will be elliptical in cross section. It is customary to add a small quantity of summer oil to the mix if the articles are to be forced through a die, in order to furnish lubrication. After the green carbon articles are formed they are Specification of LettersPatent. I. Patented J 113125, 1916, Application filed October 11, 1912. Serial ITO/725,220. I I i i usually baked to coke the binder and to.

bring about other desirable results. In the baking process the pitch swells and makes the articles porous. In most carbon articles thisporosity is objectionable and it is one cause more carbon to be deposited from this I escaping gas.

In order to make clear the swelling action of the pitch binder when the carbon articles are baked the action of pitch when baked alone will be described. If pitch. alone be heated in a crucible, it will melt to a heavy] viscous mass from which volatile matter will escape with difficulty. Under the action of v heat the mass swells and bubbles and if the process is carried until the pitch is coked it will be found to be of very porous structure due to" the action of the escaping gases.- I-Iowever, if some substance, such as ammonium sulfate, be heated with the pitch in the crucible, the action is entirely different. As-

soon as the pitch melts an immediate reaction seems to take place which causes the escape of gases and increases the viscosity of the heated pitch. The melted mass now no longer swells and bubbles, but maintains substantially constant volume and the gases readily, escape. If the mass is heated until coked its apparent density will be found to be much more than that of the coke made from the pitch alone.

If then, ammonium sulfate be mixed with pitch and carbonaceous material to form the mix and heated as previously explained, the escape of the gases immediatelyoccurs and the viscosity is increased so that more than the usual amount-of pitch' can be used as binder without being troubled with deformation of the green carbon articles which are molded or otherwise formed from this mix. This is an advantage as the pitch tends to increase the apparent density of the article during the baking process due to the shrinkage produced by the coke formed from the may be used in other forms.

If these carbon articles be now baked,

their apparent density will be much more than those made from the untreated mix". The increased density results from the absence of the bubbling and swelling of the pitch, the shrinkage due to the increased amount of coke made from the pitch and the increased amount of carbon deposited from the escape of volatile matter.

The amount of ammonium sulfate to be added depends upon the nature of the binder. and upon the desired structure of the finished product. I have found that good results are obtained if this salt amounts to 5 to 15 per cent. of the binder in certain types of forced articles,'while higher percentages The invention is therefore not be restricted to the use of ammonium sulfate in any definite amount.

There are other sulfates and sulfur-oxygen compounds besides ammonium sulfate that produce the desired results, and hence are equivalents thereof, a few of which as sodium acid-sulfate (nitercake), sodium sul-' fate (salt cake) and sulfuric acid may be mentioned. The advantage of ammonium sulfate is that it will all be removed in the process of baking and will not form an ash to contaminate the baked article. However, the amount of ash present is not a serious matter in some uses to which a carbon article is put, and therefore salt cake, nitercake and other compounds can be used in place of ammonium sulfate. Sulfuric acid. has the advantage that it acts more strongly on the pitch during the mixing process than do the other chemicals. This, of course, would increase the viscosity of the binder and increase the limiting amount that can be used. Another advantage of sulfuric acid is its lubricating properties. The mix can therefore be forced through dies Without adding any summer oil, on other lubricant to the mix.

My invention is not limited to the use of any particular binder. Pitch has been referred to as the binder simply by way of example. Tar or other hydrocarbon can be used with similar results.

It 1s old to' use sulfur 1n carbonaceous article and the action is not so marked as when sulfates and other, sulfur-oxygen com .pounds are used. The reason of this, howthe hydrocarbons. However, this may not be the action, as complex chemical com pounds may be formed due to the sulfates as such. It is easily demonstrated, however, that the articles are more dense when the sulfur compounds are 'used instead of elemental sulfur.

Due to the lack of a proper generic term, ammonium sulfate has been specified in the claims, but this expression is nevertheless intended to cover the various chemical equiva lentsof the salts, .either as 'mentionedm the specification or as knownas such.

Having described my invention what I claim is: y

1. The process of increasing the viscosity of a carbonaceous mix containing a hydrocarbon binder which consistsin adding amfate with a carbonaceous mix containing a hydrocarbon binder, heating the agglomeration, forming it into an article, and then taining coke, pitch and ammonium sulfate,

amounting to substantially 5,to 15% of the pitch CO'ltGIlt. v

5. The process of making carbon articles which consists in mixing a chemical compound containing sulfur with carbonaceous material, forming it into a shaped article and baking it.

In testimony whereof I have hereunto signed my name.

ARTHUR T. HINCKLEY. Witnesses:

FREDK. ROY, J. EMMETT Ocean. 

